After about eight hours of deliberations, a military jury found Webster M. Smith, 23, of Houston, guilty of indecent assault, extortion, sodomy, failure to obey an order and absent without leave.
The allegations were brought by four female cadets. The jury acquitted him of sexual misconduct charges involving three of the female cadets.
The indecent assault, extortion and sodomy charges of which Smith was convicted stemmed from allegations by one of the other women.
That woman described a night in which she and Smith had a series of sexual encounters in her dorm room. The woman said she never protested because she was relying on Smith to keep a secret involving a crime that could have jeopardized her career.
Prosecutors said Smith held that secret over her, extorting her for sexual favors.
Smith said that he never mentioned the secret and that the two had consensual oral sex.
Prosecutors, who had no comment after the verdict, said Webster Smith was a predator who took advantage of women when they were vulnerable.
A military jury sentenced him to six months in prison and kicked him out of the service for extorting sexual favors from a classmate. Prosecutors had asked the jury to send Smith to prison for three years, saying he had disgraced the Coast Guard and betrayed the nation's trust.